Telephone system



ug. 23, 1932. A E. FLENLEY 1,872,720

TELEPHONE SYSTEM iii.

HUI-'521:1 Edward Flax-dej www Aug. 23, A E, FLENLEY TELEPHONE sYsTM Filed Aug. 8, 1950 2 Sheets-Sheet 2 ,Imm-r Hlm Edward FZenZEE Patented Aug. 23, 1932 SATES ALFRED EDWARD FLENLEY, OF LIVERPOOL,

ENGLAND, ASSIGNOR TO ASSOCIATED '1l/ELE- LJHONE & TELEGRAPI-I COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- WARE TELEPHONE SYSTEM Application 'led August 8, 1930, Serial No. 4

The present invention relates to automatic switches for use in telephone or like systems and is more particularly concerned with socalled connector or final selector switches from the banks of which access is obtained lili to a wanted partys line. Vhere party line service is being provided it has been usual in the past to supply a special group of party line final selector switches which were different from those connecting only with individual lines in that they were provided with special ringing equipment capable of sending out the necessary ringing code for each subscriber connected to a party line. Such schemes are inclined to be extravagant in cases where the number of party lines is small compared with the number of individual lines since economical use cannot be made of the special group of party line switches.

c ylihe object of the present invention is the provision of improved circuit arrangements for final selectors whereby switches of one type only may be made to function satisfac torily in connecting with lines of both classes.

According to one feature of the invention, in a final selector switch the operation of connecting with a party line serves to disconnect ringing current of the character used for sig* nailing individual lines and render the switch responsive to a further digit for selecting ringing current of the appropriate character.

According to a further feature of the invention, the setting of a final selector switch in response to two digits automatically effects the connecting up of ringing current to the wanted line unless the digits are of predetermined value when a further digit is necessary to effect, the connecting up of ringing current.

The invention will be better understood from the following description of one method of carrying it into effect which should be taken in conjunction withthe accompanying drawings of which Fig. l shows a iinal selector of substantially known type modified in 73,866, and in Great Britainraugust e, 1929;

accordance with the principles of the invention by the addition of an auxiliary switch which establishes connection with the desired code ringing set, while Fig. 2 shows a suitable form of the code ringing set. It willbe understood that the invention is not limited to the precise arrangements shown and that various detail modifications such 'as will readily occur to those skilled in the art will come within its scope. f

Referring now to Fig. l, when thefswitch there shown is taken into use over line conductors 10 and 1l, line relay A is operated and at armature al completes a circuit for relay B which also operates. Thereupon at armature b1 it connects earth torelease trunk conductor 12 in order to hold o erated the preceding switches,rat armature 1692 prepares the circuit of the vertical magnet V, at armature 68 connects earth to conductor 13 in order to start the ringing and tone current generator, at armature b4 prepares a holding circuit for relays F, Gr and H, and at arma-- ture b5 preparesa circuit for the lower winding of relay Gr.

No further circuity changes take place until the succeeding series of impulses is received whereupon relay A cle-energizes intermittently and on each de-energization completes a circuit from earth, armatures al and b2, oli' normal springs N1, winding of slow relay C, winding of vertical magnet V'to battery. The vertical magnet V operated in this circuit to raise the shaft and wipers to the desired level and upon the first vertical step the o normal springs are shifted. Thereupon at springs Nl an alternative circuit is completed over armature 01 for the subsequent impulses to the vertical magnet, while at springs N2 a point is completed in the ciru cuit of the release magnet Z. At the end of the train of impulses relay C restores and at c its armature c1 transfers the impulsing circuit to the rotary magnet so that the next series is transmitted over armature g6, wind-` ing of sloW relay E, armature h5, Winding of rotary magnet R to battery. The rotary magnet R is accordingly operated to rotate the Wipers into engagement With the required set of contacts and relay E remains energized throughout the train of impulses and at armature el shunts armature 16 in case relay G should be operated due to Wiper P passing over busy contacts'1 at armature e3 opens a point in the circuit of the party line discriminating-relay PA, andzfat .armaturee4 opensra'point in the busy tone circuit. \More over relay E at armature e5 opens a pointin the circuit of the lower Winding of relay Gr andirt arm ature e2connectsthe upper' Winding-of this 4rela-y lover armature and back Contact to the test Wiper P.

Consider first the case of a call to-an ycrdinary subscriber in which the Want-ed line, is busy; in this case relay Gis energized when the Wipers come: to .rest ytroni-earthon the busyftest Ycontaet,.,and at armature g3 prepares a locking-circuit for -itself,v;at armature g2 Vopens .a `further peintiin thec-ircuit of ,relay-PA, at -aninaturesrgandg5 prepa-res 'points inthe code ringing circuit which are of! no: utility-in the .present instance, -at armuture'g openssa pointin the circuitoff-the rotary lmagnet iR., :at armature gf? .opens sa point in the circuit of -theaninor-sWitch :rotaryffma-gnet MR, andat armature- 78 connects :up busyxtone fromconductorxlto conductor; 11 -Whence it is `transmitted to the-calling partyls instuumentto :iarovi'de'sana audible indication-that the called line is busy. Upon the release of relayEgafter itsslow period, the lockifn-gcircuitoverzarmature g3 iscompletcd-an l relay 'GYremai-ns locked: 'npr dependent enz-armature :54. The: kcalling ,subscriber Von hearing the ',.busy tone will realize that LJae cannot obtain -rconnecti-on with the desired partyand v.will rep-lace his receiver. thereup on openingathe. circuit of relayA which I.releases andl opens: the circuit :of relay ylhenrrelay B releases, at armature b4 relayG is un- 1ocked..at armaturebl earth is removed from the releasetnulnka conductor.12;.to` permit the preceding-switches to release and` .at amiraturef 192.11 :circuit .1i s4 completed;- for the release magnet Z which l:op crates .to restore lthesxvitch to'rmrml.: in=x thc-usual manner.

:(onsider'noxvathecase .in mlrichrthe Wanted partyfis idleawvhen line is connected with; inst-his oase 'relay Gi is deenergized Whe-rr the switclrcomesto rest. and accordingly when rlay'E de-energizes7 acircuit'is completed from earth, armatures-Maand lower Winding of switching relay 1H, armature e2,-'test Wiper'Pandby :Way of .the .cut-off relay and rotary magnetofthe calledpartys line switch to; battery. fllelay Handthe cut-off relay energifie in .series inthis. circuit. and the latter clearsthe called 'line of its normal battery and earth connection. RelayH at y armata-1re515.1

completes a. locking circuit for itself o-Ver its upper Winding, at armature LQ. connects up a small condenser RB to permit a small amountof ringing current to leal; back and give the calling party ring back tone, at armature 71,3 prepares a locking circuit for relay G, at armature het opens a point in the busy tone circuit, at armature h5 opens the impuls ing circuit for the rotary magnet R, at armatures k6 and la7 connects the speaking leads through the wipers and and at armatil-'re LSfconnects direct earth to the test Wiper P in order to busy the line and hold operated. the called partys cut-olil relay. Intermi ytent current is -no-W connected up from Aconduct-or'-lover armatures 3x12 and ge, lefthand Winding of relay l", armatures and la7, jnegative Wiper and bank contact, over the called line to the positive wiper, armaturesLGjQ, g5 and perl5 ring vreturn resistance v18 to. battery, thereby ,signalling the wanted party in the usual manner. 'Villien the wanted party replies,` the dircct current bridge thereupon completed across .the speal-.ing leads servesto operatelre-lay F by Way or its lefthand Winding and atarmature fl it completes aA lockingicircuit for' itsel'fand armut uros f2 .andffconnects the speaking conductors tothe ,back bridge relay D. 'Relay l) on operatingat itsiarmature Z1 opens the start circuit to. .theringingand tone current generator and mayalso reverse the speaking leads for super- Visory purposes. Conversation may now take placelbetween 'the calling and called parties during which the battery feed to the respectiveparties issupplied by relays A and D. Atthe end ofthe conversation when thc cailinglparty replaces'his.receiver, relay A deenergizes @and at its armature al releases guard relay v.B whereupon release or' the switch takes .place in the manner previously described.

Gonsiderationfmust now'bc given to the establishment of a connection with a party linesubscriber. It will be assumed that the end ofthe second series of impulses t mitted to the switch the Wipers areset ou the contacts associated 'with a party line subscriber Whose'line is idle at this imc.

this case relay H will be operated are ously explained in series with the cal pa-rty?s cut-off rel ay-an'd in addition the au..-.. iary'test WiperPl Will encounter earth, b) means ofwhich the party line discriminating relay PA Will'be operated upon the release of relayfl -a'fter -its slow period. Relay Pri. upon operating, at its armatures yml and ,qm2 opens the normal ringing circuit of the switch and fat its armature 2m?) closes a `point circuit of the lmagnet of the auxil' 'y minor switch. Since in the system con red nulnbersof party line subscribers com; Je one more digit than those of individual. line subscribers .thecallingparty will dial a further ;digit which serves for select-ion oi 'the appropriate ringing code. These additional impulses effect the operation or" .the minor switch magnet in the circuit earth, armatures a1 and b2, oit normal springs N1, armatures c1 and 96, winding of relay E, armatures g? and 0&3 winding of magnet MR to battery. Assuming that this final digit is 1 the wipers of the minor switch will be advanced to the set of bank contacts connected .to theV code ringing set shown in Fig. 2. It will be seen that the arrangements are suitable `for up to ten parties on a line, the bells at the various substations being connected between one or other speaking lead and earth. Five code ringing sets similar to that shown in Fig. 2 are providedeach arranged to send a diterent distinctive code by suitable wiring of` the banks, and the code ringing sets may be common to all the connectors such as that shown in Fig. 1. Upon the release o-relay E at the conclusion of the inal train of impulses a circuit may be traced from earth by way of the low resistance winding of relay AA, Fig. 2, first bank Contact and wiperV 21 of the code ringing switch CR, conductor 24, iirst bank contact and wiper S of the minor switch, armatures b5, e5 and f4, lower winding of relay Gr to battery. Relay (i upon operating, at armature g1 completes a locking circuit over its upper winding and at armature g2 opens the circuit 'of relay PA which releases and disconnects the minor switch magnet MR at armature 20u13 thereby preventing any further impulses from the subscribers calling device from again operating the minor switch. Furthermore, relay Gr at its armatures g4 and g5 transfers the ringingvcircuit tothe wipers PE1 and PE2 of the minor switch to permit code ringing to take place from the selected code ringing set. V

Referring now more particularly'to Fig; 2 relay AVA, which is operated in series with relay G, at its armature m1 connects slow earth pulses over conductor 25 to the driving magnet DM of the switch CR. Accordingly the magnet commences to step the wipers 21-23 of the switch CR round the bank contacts and at the-conclusion of the first step the initial energizing circuit of relay AA is opened and the relay releases thereby opening its contacts aal. The switch continues to step however since at this time relay AB is operated over wiper 23 and shunts armature cm1 at armature 6661. No further circuit changes will take place until wiper 22 encounters bank contact 7, whereupon a circuit is completed for relayAC which operates and locks up over its armature acl to earth at armature e792. Relay AC upon operating eX- tends the earth pulse circuit to relayAE so that upon the receptioniof the next earth pulse relay AE will operate and complete the following ringing circuit: continuous ringing from earthed generator by way of conductor 26, armature acl conductor. 27, bank contact 1 and wiper PE2 of the minor switch MS., armatures g5, f2, and/t6, positive wiper and bank contact called subscribers instrument to earth.

By this means the wanted partys bell is rung for the duration of one earth pulse at the conclusion ot which the wipers of the code ringing switch CR' will be .advanced to con-` tact 8 and relay AE releases andopens the ringing circuit at armature del. When earth is next applied to conductor 25, relay AE will again be operated in parallel with the driving magnetDM and ringing current will again vbe connected up over'the circuit previously traced. This cycle of operations is' again repeated and wiper 22 of the code ringing switch CR then comes .into engagement with bank Contact 10, whereupon relay AD will be'operated and at armature @d1 will open the circuit of relay AE.` Accordingly for the duration of the next earth pulse relay AE will be prevented from operating and ringing of the called partys bell will not take place during this period. At the conclusion of this earth pulse the wipers of the codev ringing switch will be advanced to bank contacts 11 in which position relay AD will release and the circuit of relay AE is again eX- tend'ed to the conductor 25. Hence upon the reception of the next two earth pulses, relay AE will be operated in synchronism to connect up two further ringing pulses to the wanted subscribers instrument. The wipers of the code ringing switch will then have moved into vposition 13 in which the circuit for relay AB is opened and it releases thereby releasing relay AC which opens the circuit for rela-y AE. lt will be noticed, however, that assuming the connection remains set up and the called party has not replied the lower winding of relay G ,will `be connected over wiper 21 and bank contact 13 in series with low resistance relay AA to earth and upon operation of the latter relay, interrupted earth will again be connected to the driving magnet DM by way of armature (m1. Since the wiring of the two halves of the banks of the switch CE is similar, the operations above described will be repeated and a code consisticc ing of 3 rings, a short pause, 2 rings and a Moreover. relay F in operating also opens the L c'i-rcuit of thelower winding of relayGr at armature f4 so that when the code ringing switch has completed its ringing cycle, relay AA will not again be operated unless ksome oth-ervconn'ector switch isrequiring this par CTI ticular code; In case the receiver is removed during the silent.period,.that is, while :relay AE is .in its vnormal positioinrelay. .F would then have been operated from earth over :the resting'contactv kof .armature nel. It should also kbe mentioned that :in casevanotherlinal selectorswitch should select a code ringing switch while. .it is iin operation,` there is tno possibility ofa'mutilated ringing code being sent .out since the ringing circuit for the vsecond switch-will not be ycompleted until its associated G relay is operated, and this can only be elected :by .earth through .the .winding cf the start relay AA inthe code ringing switch which is only-connected up .by the wiper' .421 at `the lcommencement of a cone ringing cycle.

YYIncase abusy 4condition isencountered on a .party fline, .relay G will be operated Ibefore relay H in order` to extend the busy signal to the calling party and it will be noticed Vthat with relay G operated the impulsing circuit for theaninor switch magnet MR is opened at armature g? while similarly the circuit for the rotary :magnet R' is opened at armature gli. Consequently thereception of the 'inal code selecting digit under 'these conditions is withouteifectfdue to the opening of the irnpulsing :circuit and the associated wipers PE1, PE2 and S :remainin their normal .position so that the 'code ringing lswitch is not brought into'oper'ation in these circumstances. The minor switch 'is restored to normal after a successful vparty line call by its release magnet MZ which isconnected up over armature b3 'and off-normal springs MNl.

The final selector illustrated is not suitable for effecting 'the completion of reverti've calls and assuming that other numerical switches precede this switch in the train, specialrevertiv; 'call switches would be accessible from la particular level of one of these switches .in response tothe 'dialling` o'f'a` special revertive 4call number. The revertive call switch may then respond tothe 'last two digits of the number to send out the appropria-tel codev to ring the bells ot thecalling and called parties.

In case, however, the 'switch shown is used in an exchange of less than 1100 lines revertive calls maybe completed by an operator who is conveniently reached in response to Vthe dial ling of thedigit 0. In this case the dotted connections shown in Fig. 'l are provided, the additional off-normal 'springs N3 servingto disconnect dial tone over lead ltjas soon as'th switch lsteps oH-normal. In response to the dialling #of 0 the switch is raised to the tenth level whereupon normal post springs NPSl and NPSZ are operated, the former connecting earth to'discrimina-ting lead l0 and the latter connecting up ring-back tone to notify the calling party that thefoperator is being signalled. The voperator is provided with a lfull multiple-ot all the lines and the 'noname earthing of .lead ll0 lights a lamp associated with .the calling ypartys j ack. The operator on seeing the lamp light plugs in to the jackin orderto ascertain the subscribers wishes,this operation energizing a relay connected to the sleevezof the ack which e'lfects the release of the final Vselector switch and .also connects earth to the private normal conductor'to busy the-line.

@n hearing that a revertive call is required the operator vwill ask the calling party to hang up hisreceiver andv will then send out the ringing code Vier the desired party. lhen he replies, thecalling subscriber will again remove his receiver and conversation may take place, battery feed for both parties' being supplied from the yoperators cord circuit.

W7 hat I claim is l. In a telephone system, an automatic numerical switch having access to different classes of imes, means for operating said switch responsive to a. plurality ot digits of a calledv telephone number -to seize Yone of said lines, and means operated over a `wiper oi said switch only in case the seized line is oi a. particular one ot said classes for preparing said switch to respond to a further digit.

2. In a telephone system7 a connector switch, means for operating said switch responsive toa plurality of digitsv to connect with a desired called line, a selective ringing switch associ-ated with saidv connector, and means for operating said selective ringing switch responsive to a further digit vonly in case said plurality of digits were fof particular predetermined values.

3. In a telephone system, a connector switch having access to individual and party lines, means for operating said switch into enga-gement with one of said lines, means for ringing the called line in case an individual line is connected with, and means edective in case a Aparty line has been connected with for disabling said ringing means and for rendering said switch responsive to a further digit.

el. In atelephone system, a connector switch having access to subscribers lines, means responsive to two ldigits of a called number for operating said switch into engagement with one of said lines, means for automatically connecting ringing current lto the called line, and means effective in case said two digits are of particular predetermined values for disabling said ringing means until a third digit hasbeen received.

5. In a telephone system, a connector switch having access to individual and party lines, means oroperating said switch into engagement with one of said lines'responsive to two digits of a called number, means for ringing an idle individual line when connected with, and means controlled over a wiper of said switch when the switch is operated into engagement with an idle party line for disloa lill

abling said ringing means and for preparing Isaid switch to respond to a further digit.

6. In a telephone system, a connector switch having access to individual and party lines, means for operating said switch into engagement with one of said lines, means for ringing the called line in case an individual line has been connected with, means effective in case a part-y line is connected with for disabling said ringing means and for rendering said switch responsive to a Jfurther digit, a plurality of code ringing switches, and means responsive to said further digit for selecting the proper code ringing switch to signal the Wanted subscriber on'the party line.

7. In a telephone system, a connector switch having access to individual and party lines, means for operating said switch into engagement with one of said lines, a busy relay operated in case the called line is busy to connect busy tone to the incoming line conductors, means for automatically connecting ringing current to an idle individual line when connected with, means eiective in case an idle party line has been connected with for disabling said ringing means and rendering said switch responsive to a third digit, and means for operating said busy relay to connect ringing current to the called party line after said third digit has been received.

8. In a telephone system, a connector switch having access to subscribers lines, means responsive to two digits of a called number for operating said switch into engagement with one of said lines, means for automatically connecting ringing current to the called line, means eective in case said two digits are of particular predetermined values for disabling said ringing means and for preparing said switch to respond to a third digit, a plurality of sources of ringing current having different characteristics, and means responsive to said third digit for selecting ringing current of the proper characteristic.

9. In a telephone system, a connector switch having access to individual and party lines, means for operating said switch to connect with one of said lines responsive to two digits of a called number, means for ringing an idle individual line when seized, a minor switch. means eiiective in case an idle party line is seized for disabling said ringing means and for preparing an operating circuit Jfor said minor switch, and means responsive to the operation of said minor switch by a further digit or ringing the wanted subscriber on the party line.

10. In a telephone system, a connector switch having access to two classes of lines, means responsive to two digits of a called vnumber for operating said switch into engagement with one of said lines, means for signalling said line in case it is of a certain class, and discriminating means for disabling said signalling means and for preparing said switch to respond to a further digit in case said line is of the other class.

11. In a telephone system, an automatic numerical switch having access to two classes of lines, means for operating said switch responsive to two series of impulses to seize one of said lines, an auxiliary switch associated with said numerical switch, means Jfor operating said auxiliary switch responsive to a third series of impulses in case a line of one class is seized, and means for preventing the operation of said auxiliary switch in case a line of the other class is seized.

In testimony whereof I aiiix my signature.

ALFRED E. FLENLEY. 

